Although the present invention is described below with reference to projectors for video glasses, it is not limited thereto. Rather, the present invention may be used with any arbitrary projectors, such as projectors for head-up displays in vehicles.
Projectors are currently used in numerous applications, in particular so-called miniature projectors or microprojectors, also in mobile form.
Mobile applications may be, for example, video glasses or display devices for mounting on glasses. In such applications, information may be projected to a user directly into his/her visual field and superimposed on the field of view of the user.
It is known to use projectors, having a laser light source and a laser scanner or MEMS mirror, for example, for mobile operation, since these projectors may be designed for a very small installation space.
Glasses having such a display device, i.e., video glasses, are put on by a user and worn on the head, i.e., on the face. Therefore, these projectors must be as small and lightweight as possible. In addition, the projector should have a preferably long operating period on one battery charge.
Due to the fastening of the projector and the battery to the glasses and on the head of the user, the size of the battery, and therefore its capacity, is also limited. In order to still achieve a long run time of the projector on one battery charge, it is necessary to reduce the energy consumption of the projector.
To meet the requirements for low energy consumption, in present projectors the laser diodes as well as the MEMS scanners and the video electronics are optimized in order to reduce their energy demand. In addition, more efficient concepts for supplying power to the projectors are being developed.
United States Published Patent Appln. No. 20130070209 describes, for example, a projector having MEMS mirrors in which the intensity of the laser light source is set as a function of the contrast of a scan line.
However, the mentioned measures still do not allow extended operation of such a projector during mobile use with satisfactory autonomy.
Therefore, there is a need to further reduce the energy consumption of projectors, in particular projectors for mobile use.